<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        <!--通过标签名选择器找到元素-->
        h2{color:green}
    </style>
</head>
<body>
<h1 style="color:red">内联测试1</h1>
<h1 style="color:red">内联测试2</h1>
<h2>内部样式1</h2>
<h2>内部样式2</h2>
<h3>外部样式1</h3>
<h3>外部样式2</h3>
</body>
</html>